Demineralized bone matrix fibers, methods of making and using them

ABSTRACT

A device for mixing a bone material with a liquid is provided. The device comprises a chamber having a proximal end and a distal end, and the bone material disposed within the chamber, the bone material comprising a DBM pellet of milled and lyophilized demineralized bone fibers; and a plunger having at least a portion slidably disposed within the proximal end of the chamber and configured to dispense the bone material mixed with liquid from the distal end of the chamber, when the plunger is in an extended position.

BACKGROUND

It is estimated that more than half a million bone grafting procedures are performed in the United States annually with a cost over $2.5 billion. These numbers are expected to double by 2020. Both natural bone and bone substitutes have been used as bone material in bone grafts. Natural bone may be autograft or allograft. Bone substitutes include natural or synthetic materials such as collagen, silicone, acrylics, calcium phosphate, calcium sulfate, or the like.

There are at least three ways in which a bone graft can help repair a defect. The first is osteogenesis, the formation of new bone within the graft by the presence of bone-forming cells called osteoprogenitor cells. The second is osteoinduction, a process in which molecules contained within the graft (e.g., bone morphogenic proteins and other growth factors) convert progenitor cells into bone-forming cells. The third is osteoconduction, a physical effect by which a matrix, often containing graft material, acts as a scaffold on which bone and cells in the recipient are able to form. The scaffolds promote the migration, proliferation and differentiation of bone cells for bone regeneration.

Demineralized bone matrix (DBM) is a type of bone material that has been shown to exhibit the ability to induce and/or conduct the formation of bone. It is therefore desirable to implant and maintain demineralized bone matrix at a site in which bone growth is desired.

Bone fiber-based demineralized bone matrices for implantation exhibit improvements in mechanical properties, including cohesiveness, fiber length, fiber diameter or width, fiber aspect ratio, or a combination of multiple variables.

Sometimes DBM fibers, when hydrated in a closed system such as a chamber or syringe, have inconsistent handling characteristics. The DBM fibers can be improperly hydrated where the hydration of the DBM fibers is not uniform causing the syringe or chamber to clog on mixing and dispensing the DBM fibers.

Therefore, there is a need for bone material containing DBM fiber that allows the DBM fibers to be uniformly hydrated in the syringe or chamber before delivery. DBM fibers, devices to mix and deliver DBM fibers and methods of making DBM fibers comprising a combination of long fiber sizes and short fiber sizes that enhance hydration would be most beneficial.

SUMMARY

DBM fibers, devices to mix and deliver DBM fibers and methods of making DBM fibers comprising a combination of long fiber sizes and short fiber sizes that enhance hydration are provided.

In some embodiments, a method of preparing a demineralized bone matrix pellet is provided. The method comprises providing a plurality of long bone fibers having a diameter from about 0.5 mm to about 8.0 mm; mixing the plurality of long bone fibers with a plurality of short bone fibers having a diameter from about 0.5 mm to about 0.05 mm to form a mixture of long bone fibers and short bone fibers; demineralizing the mixture of long bone fibers and short bone fibers to form a demineralized bone matrix slurry; and drying the demineralized bone matrix slurry to form a demineralized bone matrix pellet.

In some embodiments, a bone material comprising a mixture of a plurality of long bone fibers having a diameter from about 0.5 mm to about 8.0 mm and a plurality of short bone fibers having a diameter from about 0.5 mm to about 0.05 mm is provided.

Additional features and advantages of various embodiments will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practice of various embodiments. The objectives and other advantages of various embodiments will be realized and attained by means of the elements and combinations particularly pointed out in the description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In part, other aspects, features, benefits and advantages of the embodiments will be apparent with regard to the following description, appended claims and accompanying drawings.

FIG. 1A illustrates an embodiment of a method of manufacturing of DBM pellets from large bone fibers. Large bone fibers are sieved, selected and categorized into long fibers and short fibers. The long fibers and short fibers are mixed to form a DBM slurry. The DBM slurry is added to a mold to form a pellet and dried.

FIG. 1B illustrates an embodiment of a method of manufacturing DBM pellets from large bone fibers. Large bone fibers are sieved, selected and categorized into long fibers and short fibers. The long fibers and short fibers are mixed to form a DBM slurry. The DBM slurry is allowed to drain and then added to a mold to form pellet shapes, the pellets are freeze dried and then removed from the mold in pellet form.

FIG. 2 depicts an embodiment of long fibers. Large bone fibers are milled from a piece of bone and place in a sieve to obtain the long bone fibers of the desired size.

FIG. 3 depicts an embodiment of short fibers. The remainder of large fibers are milled into short fibers.

FIG. 4 depicts an embodiment of a DBM slurry. The targeted long fibers and the short fibers are mixed and demineralized to form a DBM slurry containing now both large demineralized and short demineralized fibers.

FIG. 5A depicts an embodiment of packing a portion of the DBM slurry into a mold. The DBM slurry is lightly compacted into a mold by a spatula.

FIG. 5B depicts an embodiment of packing the DBM slurry into a mold. The DBM slurry is lightly compacted by a spatula into the mold, where the DBM slurry takes the shape of the mold having substantially uniform sizes and pellet shapes.

FIG. 6A depicts an embodiment of packing the DBM slurry into a mold. The DBM slurry is lightly compacted into the mold by a roller and a compression block.

FIG. 6B depicts an embodiment of packed DBM slurry in the mold. The DBM slurry is lightly compacted by a roller and a compression block into the mold to form the DBM pellets having uniform sizes and shapes.

FIG. 7A depicts an embodiment of DBM pellets after they are ejected from the mold. The DBM pellets are dried and the pellets are in a sheet.

FIG. 7B depicts an embodiment of DBM pellets. The DBM pellets are knocked out individually and/or in sheet form for drying.

FIG. 8A depicts an embodiment of DBM pellets. The dried DBM pellets are in sheet form having uniform sizes and shapes.

FIG. 8B depicts an embodiment of DBM pellets. The dried DBM pellets have a uniform size and shape and are separated individually.

FIG. 8C depicts an embodiment of DBM pellets. The dried DBM pellets are in sheet form with pellets being detached from the sheet.

FIG. 9 illustrates an embodiment of a texture analyzer for measuring handling texture of the DBM pellets.

FIG. 10 illustrates an embodiment of a syringe or chamber loaded with dried DBM fiber pellets.

FIG. 11 illustrates an embodiment where the dried DBM pellets are hydrated with liquid. The liquid comprises blood and the plunger has been moved between a retracted position and an extended position 20 times to hydrate the DBM pellets.

FIG. 12 illustrates a graph correlating the relationship between the hydration of the DBM pellets and the injection force exerted on the DBM pellets. The graph also depicts different results from different volumes of the liquid added to the dried DBM pellets.

It is to be understood that the figures are not drawn to scale. Further, the relationship between objects in a figure may not be to scale and may, in fact, have a reverse relationship as to size. The figures are intended to bring understanding and clarity to the structure of each object shown, and thus, some features may be exaggerated in order to illustrate a specific feature of a structure.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to certain embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the disclosure as described herein being contemplated as would normally occur to one skilled in the art to which the disclosure relates.

For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities of ingredients, percentages or proportions of materials, reaction conditions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present application. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical representations are as precise as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a range of “1 to 10” includes any and all subranges between (and including) the minimum value of 1 and the maximum value of 10, that is, any and all subranges having a minimum value of equal to or greater than 1 and a maximum value of equal to or less than 10, e.g., 5.5 to 10.

Additionally, unless defined otherwise or apparent from context, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

Unless explicitly stated or apparent from context, the following terms are phrases have the definitions provided below:

Definitions

It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. Thus, for example, reference to “an allograft” includes one, two, three or more allografts.

The term “biodegradable” includes that all or parts of the carrier and/or implant will degrade over time by the action of enzymes, by hydrolytic action and/or by other similar mechanisms in the human body. In various embodiments, “biodegradable” includes that the carrier and/or implant can break down or degrade within the body to non-toxic components after or while a therapeutic agent has been or is being released. By “bioerodible” it is meant that the carrier and/or implant will erode or degrade over time due, at least in part, to contact with substances found in the surrounding tissue, fluids or by cellular action.

The term “mammal” refers to organisms from the taxonomy class “mammalian,” including but not limited to humans, other primates such as chimpanzees, apes, orangutans and monkeys, rats, mice, cats, dogs, cows, horses, etc.

A “therapeutically effective amount” or “effective amount” is such that when administered, the drug (e.g., growth factor) results in alteration of the biological activity, such as, for example, promotion of bone, cartilage and/or other tissue (e.g., vascular tissue) growth, inhibition of inflammation, reduction or alleviation of pain, improvement in the condition through inhibition of an immunologic response, etc. The dosage administered to a patient can be as single or multiple doses depending upon a variety of factors, including the drug's administered pharmacokinetic properties, the route of administration, patient conditions and characteristics (sex, age, body weight, health, size, etc.), extent of symptoms, concurrent treatments, frequency of treatment and the effect desired. In some embodiments the implant is designed for immediate release. In other embodiments the implant is designed for sustained release. In other embodiments, the implant comprises one or more immediate release surfaces and one or more sustained release surfaces.

The terms “treating” and “treatment” when used in connection with a disease or condition refer to executing a protocol that may include a bone repair procedure, where the bone implant and/or one or more drugs are administered to a patient (human, other normal or otherwise or other mammal), in an effort to alleviate signs or symptoms of the disease or condition or immunological response. Alleviation can occur prior to signs or symptoms of the disease or condition appearing, as well as after their appearance. Thus, treating or treatment includes preventing or prevention of disease or undesirable condition. In addition, treating, treatment, preventing or prevention do not require complete alleviation of signs or symptoms, does not require a cure, and specifically includes protocols that have only a marginal effect on the patient.

The term “bone,” as used herein, refers to bone that is cortical, cancellous or cortico-cancellous of autogenous, allogeneic, xenogeneic, or transgenic origin.

The term “allograft” refers to a graft of tissue obtained from a donor of the same species as, but with a different genetic make-up from, the recipient, as a tissue transplant between two humans.

The term “autologous” refers to being derived or transferred from the same individual's body, such as for example an autologous bone marrow transplant.

The term “osteoconductive,” as used herein, refers to the ability of a non-osteoinductive substance to serve as a suitable template or substance along which bone may grow.

The term “osteoinductive,” as used herein, refers to the quality of being able to recruit cells from the host that have the potential to stimulate new bone formation. Any material that can induce the formation of ectopic bone in the soft tissue of an animal is considered osteoinductive.

The term “osteoinduction” refers to the ability to stimulate the proliferation and differentiation of pluripotent mesenchymal stem cells (MSCs). In endochondral bone formation, stem cells differentiate into chondroblasts and chondrocytes, laying down a cartilaginous ECM, which subsequently calcifies and is remodeled into lamellar bone. In intramembranous bone formation, the stem cells differentiate directly into osteoblasts, which form bone through direct mechanisms. Osteoinduction can be stimulated by osteogenic growth factors, although some ECM proteins can also drive progenitor cells toward the osteogenic phenotype.

The term “osteoconduction” refers to the ability to stimulate the attachment, migration, and distribution of vascular and osteogenic cells within the graft material. The physical characteristics that affect the graft's osteoconductive activity include porosity, pore size, and three-dimensional architecture. In addition, direct biochemical interactions between matrix proteins and cell surface receptors play a major role in the host's response to the graft material.

The term “osteogenic” refers to the ability of a graft material to produce bone independently. To have direct osteogenic activity, the graft must contain cellular components that directly induce bone formation. For example, an allograft seeded with activated MSCs would have the potential to induce bone formation directly, without recruitment and activation of host MSC populations. Because many osteoconductive allografts also have the ability to bind and deliver bioactive molecules, their osteoinductive potential will be greatly enhanced.

The term “osteoimplant,” as used herein, refers to any bone-derived implant prepared in accordance with the embodiments of this disclosure and, therefore, is intended to include expressions such as bone membrane or bone graft.

The term “patient” refers to a biological system to which a treatment can be administered. A biological system can include, for example, an individual cell, a set of cells (e.g., a cell culture), an organ, or a tissue. Additionally, the term “patient” can refer to animals, including, without limitation, humans.

The term “demineralized,” as used herein, refers to any material generated by removing mineral material from tissue, e.g., bone tissue. In certain embodiments, the demineralized compositions described herein include preparations containing less than 5%, 4%, 3%, 2% or 1% calcium by weight. Partially demineralized bone (e.g., preparations with greater than 5% calcium by weight but containing less than 100% of the original starting amount of calcium) is also considered within the scope of the disclosure. In some embodiments, partially demineralized bone contains preparations with greater than 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% of the original starting amount of calcium. In some embodiments, demineralized bone has less than 95% of its original mineral content. In some embodiments, demineralized bone has less than 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, or 5% of its original mineral content. Demineralized is intended to encompass such expressions as “substantially demineralized,” “partially demineralized,” and “fully demineralized.” In some embodiments, part or all of the surface of the bone can be demineralized. For example, part or all of the surface of the allograft can be demineralized to a depth of from about 100 to about 5000 microns, or about 150 microns to about 1000 microns. In some embodiments, part or all of the surface of the allograft can be demineralized to a depth of from about 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2350, 2400, 2450, 2500, 2550, 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, 3000, 3050, 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3800, 3850, 3900, 3950, 4000, 4050, 4100, 4150, 4200, 4250, 4300, 4350, 4400, 4450, 4500, 4550, 4600, 4650, 4700, 4750, 4800, 4850, 4900, 4950 to about 5000 microns. If desired, the outer surface of the intervertebral implant can be masked with an acid resistant coating or otherwise treated to selectively demineralize unmasked portions of the outer surface of the intervertebral implant so that the surface demineralization is at discrete positions on the implant.

The term “demineralized bone matrix,” as used herein, refers to any material generated by removing mineral material from bone tissue. In some embodiments, the DBM compositions as used herein include preparations containing less than 5%, 4%, 3%, 2% or 1% calcium by weight.

The term “superficially demineralized,” as used herein, refers to bone-derived elements possessing at least about 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99 weight percent of their original inorganic mineral content. The expression “partially demineralized” as used herein refers to bone-derived elements possessing from about 8 to about 90 weight percent of their original inorganic mineral content. In some embodiments, partially demineralized refers to bone-derived elements possessing from about 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88 to about 90 weight percent of their original inorganic mineral content. The expression “fully demineralized” as used herein refers to bone containing less than 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% of its original mineral context.

The terms “pulverized bone”, “powdered bone” or “bone powder” as used herein, refers to bone particles of a wide range of average particle size ranging from relatively fine powders to coarse grains and even larger chips.

The allograft can comprise bone fibers. Fibers include bone elements whose average length to average thickness ratio or aspect ratio of the fiber is from about 50:1 to about 1000:1. In overall appearance the fibrous bone elements can be described as elongated bone fibers, threads, narrow strips, or thin sheets. Often, where thin sheets are produced, their edges tend to curl up toward each other. The fibrous bone elements can be substantially linear in appearance or they can be coiled to resemble springs. In some embodiments, the elongated bone fibers are of irregular shapes including, for example, linear, serpentine or curved shapes. The elongated bone fibers are preferably demineralized, however, some of the original mineral content may be retained when desirable for a particular embodiment. The fibers when wet relax because they are porous, as they dry, they become more entangled and form a DBM pellet as the fibers interconnect. In some embodiments, even when the fibers are wet, they are still cohesive.

“Non-fibrous”, as used herein, refers to elements that have an average width substantially smaller than the average thickness of the fibrous bone element or aspect ratio of less than from about 50:1 to about 1000:1. For example, allograft bone fibers will have a fiber shape, while the non-fibrous material will not have a fiber shape but will have a shape such as, for example, triangular prism, sphere, cube, cylinder, square, triangle, particle, powder, and other regular or irregular shapes.

“Pressed bone fibers”, as used herein, refer to bone fibers formed by applying pressure to bone stock. The bone utilized as the starting, or stock, material may range in size from relatively small pieces of bone to bone of such dimensions as to be recognizable as to its anatomical origin. The bone may be substantially fully demineralized, surface demineralized, partially demineralized, or nondemineralized. In general, the pieces or sections of whole bone stock can range from about 1 to about 400 mm, from about 5 to about 100 mm, in median length, from about 0.5 to about 20 mm, or from about 2 to about 10 mm, in median thickness and from about 1 to about 20 mm, or from about 2 to about 10 mm, in median width. Forming bone fibers by pressing results in intact bone fibers of longer length than other methods of producing the elongate bone fibers retaining more of the native collagen structure. The bone fibers may be made via a cartridge mill.

“High porosity”, as used herein refers to having a pore structure that is conducive to cell ingrowth, and the ability to promote cell adhesion, proliferation and differentiation.

“Resorbable”, as used herein, refers to a material that exhibits chemical dissolution when placed in a mammalian body.

“Bioactive agent” or “bioactive compound”, as used herein, refers to a compound or entity that alters, inhibits, activates, or otherwise affects biological or chemical events. For example, bioactive agents may include, but are not limited to, osteogenic or chondrogenic proteins or peptides, anti-AIDS substances, anti-cancer substances, antibiotics, immunosuppressants, anti-viral substances, enzyme inhibitors, hormones, neurotoxins, opioids, hypnotics, anti-histamines, lubricants, tranquilizers, anti-convulsants, muscle relaxants and anti-Parkinson substances, anti-spasmodics and muscle contractants including channel blockers, miotics and anti-cholinergics, anti-glaucoma compounds, anti-parasite and/or anti-protozoal compounds, modulators of cell-extracellular matrix interactions including cell growth inhibitors and antiadhesion molecules, vasodilating agents, inhibitors of DNA, RNA or protein synthesis, anti-hypertensives, analgesics, anti-pyretics, steroidal and non-steroidal anti-inflammatory agents, anti-angiogenic factors, angiogenic factors, anti-secretory factors, anticoagulants and/or antithrombotic agents, local anesthetics, ophthalmics, prostaglandins, anti-depressants, anti-psychotic substances, anti-emetics, and imaging agents. In certain embodiments, the bioactive agent is a drug. In some embodiments, the bioactive agent is a growth factor, cytokine, extracellular matrix molecule or a fragment or derivative thereof, for example, a cell attachment sequence such as RGD.

The term “flowable” includes that the composition can be administered in an injectable state via a syringe and/or cannula. The composition is flowable when its consistency is fluid-like and has a viscosity that is lower than that of the viscosity of the composition when in a putty or paste form. Flowable compositions include liquid or fluid (e.g., solution, suspension, or the like) or semi-solid compositions (e.g., gels) that are easy to manipulate and may be brushed, sprayed, dripped, injected, shaped and/or molded at or near the target tissue site. “Flowable” includes compositions with a low viscosity or water-like consistency to those with a high viscosity, such as a paste-like material. In various embodiments, the flowability of the composition allows it to conform to irregularities, crevices, cracks, and/or voids in the bone defect site (e.g., bone void). For example, in various embodiments, the composition may be used to fill one or more voids in an osteolytic lesion.

The term “injectable” refers to a mode of administering the composition. The composition can be administered in a variety of ways such as, for example, a syringe and/or cannula. For example, the composition can be administered parenterally, such as for example, anterior lumbar interbody administration for fusion, or posterior lumbar interbody administration for fusion or transforaminal lumbar interbody administration for fusion, other intraspinal injection or other local administration.

The term “hydrate,” “hydration,” “hydratable,” “hydrating’ or “hydrated” refers to adding an amount of fluid to the bone material to increase the amount of moisture content in the composition to make it flowable or injectable.

The term “dehydrated” or “dehydration” refers to a composition that contains a small amount of residual moisture or no moisture content and can be in the form of a dry composition. The dehydrated composition can have a moisture content from about 0 to about 10% based on the total weight of the composition. In some embodiments, when a composition is dehydrated, fluid can be added to the composition to hydrate the composition. A dehydrated composition includes a lyophilized or freeze-dried composition.

The term “bone marrow aspirate” or “BMA” refers to the withdrawal of bone marrow fluid through a syringe and needle to harvest the bone marrow fluid from the patient. Bone marrow aspirate comprises fluid that contains a heterogeneous mix of stem and progenitor cells, platelets and white blood cells. The bone marrow aspirate can be harvested from various sources in the body, including, but not limited to the iliac crest.

Reference will now be made in detail to certain embodiments of the disclosure. The disclosure is intended to cover all alternatives, modifications, and equivalents that may be included within the disclosure as defined by the appended claims.

The headings below are not meant to limit the disclosure in any way; embodiments under any one heading may be used in conjunction with embodiments under any other heading.

It will be apparent to those skilled in the art that various modifications and variations can be made to various embodiments described herein without departing from the spirit or scope of the teachings herein. Thus, it is intended that various embodiments cover other modifications and variations of various embodiments within the scope of the present teachings.

Methods of Making Demineralized Bone Fibers

DBM fibers, devices to mix and deliver DBM fibers and methods of making DBM fibers comprising a combination of long fiber sizes and short fiber sizes that enhance hydration are provided.

During the milling process, cortical bone fibers are generally produced in various shapes and sizes. Methods of making demineralized bone matrix pellets are provided that can be tailored to have a specific size in order to achieve optimal re-hydration and ejectability characteristics for use in injectable compositions to repair bone. As illustrated in FIG. 1A, in one embodiment, a method of making demineralized bone pellets of sizes sufficient to pass through the cannula of a chamber or syringe is provided. The method comprises sieving 22 out large bone fibers longer than a long bone fiber having a targeted diameter of approximately greater than 4.0 mm. In some embodiments, after milling and grinding, the large bone fibers may be sieved to select those fibers of a desired size. In certain embodiments, the bone fibers may be sieved though a 0.5 mm sieve, a 1 mm micron sieve, a 2 mm sieve, a 3 mm sieve, a 4 mm sieve, a 5 mm sieve, a 6 mm sieve, a 7 mm sieve and/or an 8 mm sieve.

After the sieving, in some embodiments, a plurality of long bone fibers 126 having a diameter from about 0.5 mm to about 8.0 mm, from about 0.5 mm to about 1 mm, from about 1 mm to about 2 mm, from about 2 mm to about 3 mm, from about 3 mm to about 4 mm, from about 4 mm to about 5 mm, from about 5 mm to about 6 mm, from about 6 mm to about 7 mm, or from about 6 mm to about 8 mm is provided. In some embodiments, the long fibers have a diameter range from about 0.5 mm to about 4 mm. An embodiment of long bone fibers is shown in FIG. 2.

As is well known, the most widely used method of describing bone fiber size distributions are D values. The D10, D50 and D90 are commonly used to represent the midpoint and range of the bone fiber sizes of a given sample. In particular, the bone fiber size distribution D50 is also known as the median length or the medium value of the bone fiber size distribution, it is the value of the bone fiber length at 50% in the cumulative distribution, D10 is the size of the bone fiber sample below which 10% of the sample lies and D90 is the size of the bone fiber sample below which 90% of the sample lies. In some embodiments, the D50 value of the long bone fibers described in this disclosure varies from about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 to about 0.9 mm.

In some embodiments, the method comprises milling 24 the remainder large bone fibers that were sieved out. The milled bone fibers are milled into a plurality of short bone fibers. In some embodiments, a plurality of short bone fibers 128 is produced having a diameter from about 0.5 mm to about 0.05 mm In some embodiments, the short bone fibers have a range from about 0.5 mm to about 0.4 mm, from about 0.4 mm to about 0.3 mm, from about 0.3 mm to about 0.2 mm, from about 0.2 mm to about 0.1 mm, from about 0.1 mm to about 0.09 mm, from about 0.09 mm to about 0.08 mm, from about 0.08 mm to about 0.07 mm, from about 0.07 mm to 0.06 mm, or from about 0.06 mm to about 0.05 mm is provided. In some embodiments, the short bone fibers have a range from about 0.5 mm to about 0.106 mm. In some embodiments, the D50 value of the short bone fibers described in this disclosure varies from about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08 to about 0.09 mm.

An embodiment of short bone fibers is shown in FIG. 3. In some embodiments, the method comprises providing the long bone fibers 26 and providing the short bone fibers 28. In some embodiments, the method further comprises the plurality of long bone fibers being mixed with the plurality of short bone fibers to form a mixture, which is demineralized forming a demineralized bone matrix (DBM) slurry 30.

An embodiment of a demineralized bone slurry is shown in FIG. 4 as 130; the demineralized bone matrix slurry being lightly packed or compacted 32 into a mold 150 to form pellets 134, for example, as shown in FIGS. 5A, 5B, 6A and 6B; removing DBM pellets from the mold 34, for example as shown in FIGS. 7A and 7B; and freeze drying 36 the pellets in sheet form or individually, for example, as shown in FIGS. 8A, 8B and 8C.

Another embodiment of a method of making demineralized bone pellets of sizes sufficient to pass through the cannula of a chamber or syringe is provided in FIG. 1B. The method illustrated in FIG. 1B comprises sieving 22 out large bone fibers longer than a long bone fiber having a targeted diameter of approximately greater than 4.0 mm. In some embodiments, after milling and grinding, the large bone fibers may be sieved to select those fibers of a desired size. In certain embodiments, the bone fibers may be sieved though a 0.5 mm sieve, a 1 mm micron sieve, a 2 mm sieve, a 3 mm sieve, a 4 mm sieve, a 5 mm sieve, a 6 mm sieve, a 7 mm sieve and/or an 8 mm sieve. The remainder of large bone fibers that were sieved out can be milled 24 into short bone fibers of 0.5-0.1 mm in diameter. In some embodiments, the short bone fibers have a range from about 0.5 mm to about 0.4 mm, from about 0.4 mm to about 0.3 mm, from about 0.3 mm to about 0.2 mm, from about 0.2 mm to about 0.1 mm, from about 0.1 mm to about 0.09 mm, from about 0.09 mm to about 0.08 mm, from about 0.08 mm to about 0.07 mm, from about 0.07 mm to 0.06 mm, or from about 0.06 mm to about 0.05 mm is provided. In some embodiments, the short bone fibers have a range from about 0.5 mm to about 0.106 mm. In some embodiments, the D50 value of the short bone fibers described in this disclosure varies from about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08 to about 0.09 mm.

The method illustrated in FIG. 1B comprises providing the long bone fibers 26 and providing the short bone fibers 28. In some embodiments, the method further comprises mixing the plurality of long bone fibers with the plurality of short bone fibers to form a mixture, which is demineralized forming a demineralized bone matrix (DBM) slurry 30. In some aspects, the method includes allowing the DBM slurry to drain 31, followed by adding the slurry into a mold 32 to form pellets, freeze drying the pellets 33 and then removing the pellets 35 from the mold.

In some embodiments, the mixture of the long bone fibers and short bone fibers is demineralized in a slurry. In one embodiment, a slurry is made of the long and short fibers, which have been milled down to an appropriate particle size, as discussed herein. Water or a saline solution, for example, may be used to form a slurry. In some embodiments, when making a slurry comprising the DBM bone fibers, it may be desirable to select a solution that does not cause swelling of the DBM bone fibers, or which prevents swelling of the DBM bone fibers, as uneven swelling may alter the characteristics of the mixture of the DBM bone fibers. For example, a solution of ethanol may be used to create a slurry with the DBM bone fibers. Other types of solutions such as hypertonic aqueous salt or sugar solutions may also be advantageous to achieve this result.

In one demineralization procedure, the mixed long and short bone fibers are subjected to an acid demineralization step followed by a defatting/disinfecting step. The bone fibers are immersed in acid to effect demineralization. Acids that can be employed in this step include inorganic acids such as hydrochloric acid and as well as organic acids such as formic acid, acetic acid, peracetic acid, citric acid, propionic acid, and the like. The depth of demineralization into the bone surface can be controlled by adjusting the treatment time, temperature of the demineralizing solution, concentration of the demineralizing solution, and agitation intensity during treatment. Thus, in various embodiments, the DBM bone fibers may be fully demineralized, partially demineralized, or surface demineralized. Suitable demineralization techniques are described in U.S. Ser. No. 15/906,788, which was filed on Feb. 27, 2018 and published as U.S. Patent Publication No. 20180185548, assigned to Warsaw Orthopedic, Inc. Warsaw, Ind., USA. The entire disclosure is herein incorporated by reference into the present disclosure.

The demineralized bone fibers are rinsed with sterile water and/or buffered solution(s) to remove residual amounts of acid and thereby raise the pH. A suitable defatting/disinfectant solution is an aqueous solution of ethanol, the ethanol being a good solvent for lipids and the water being a good hydrophilic carrier to enable the solution to penetrate more deeply into the bone particles. The aqueous ethanol solution also disinfects the bone by killing vegetative microorganisms and viruses. Ordinarily, at least about 10 to 40 percent by weight of water (i.e., about 60 to 90 weight percent of defatting agent such as alcohol) is present in the defatting disinfecting solution to produce optimal lipid removal and disinfection within a given period of time. A suitable concentration range of the defatting solution is from about 60 to about 85 weight percent alcohol, or about 70 weight percent alcohol. In some embodiments, a suitable concentration of the defatting solution is from about 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84 to about 85 weight percent alcohol.

In some embodiments, the demineralized bone matrix slurry is added to a mold and dried in the mold or dried outside of the mold. In some embodiments, the demineralized bone matrix slurry is compacted into a mold using a pressure from about 4 to about 65 Newtons. In some embodiments, the DBM slurry is compacted manually by a tool, for example, a spatula 152, as shown in FIG. 5A. In some embodiments, the DBM slurry is packed into the mold by a roller 154 and compacted by a compression block 156 in FIG. 6A and FIG. 6B. In some embodiments no compression is applied after packing the DBM slurry into the molds and the demineralized bone matrix slurry is allowed to drain in a sieve until the excess fluid is drained from the slurry.

In some embodiments, the DBM slurry is added to a mold to form the demineralized bone matrix pellets as the mold has a pellet shape. The pellets are removed from the mold and lyophilized. In some embodiments the pellets are lyophilized then removed from the mold. In some embodiments, the method further comprises rehydrating the lyophilized demineralized bone matrix pellet with physiologically acceptable liquid to form an injectable demineralized bone matrix. In some embodiments, the liquid comprises bone marrow aspirate, saline, sterile water, blood for injection, phosphate buffered saline, dextrose, Ringer's lactated solution, or a combination thereof.

In some embodiments, the liquid used to hydrate the DBM pellets can include sterile water, saline, phosphate buffered saline (PBS), hyaluronic acid, cellulose ethers (such as carboxymethyl cellulose), water, collagen, gelatin, autoclaved bone powder, osteoconductive carriers, whole blood, blood fractions, concentrated bone marrow aspirate, and mixtures thereof. Non-limiting examples of blood fractions include serum, plasma, platelet-rich plasma, concentrated platelet-rich plasma, platelet-poor plasma, and concentrated platelet poor plasma.

In some embodiments, the ratio of fluid to pellets can be from about 0.5:1 v/v to about 2:1 v/v. In some embodiments, the ratio of fluid to pellets can be from about 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1:1.1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 to about 2:1 v/v. In some embodiments, the pellets can be hydrated with bone marrow aspirate at a 1:1 v/v.

FIG. 11, for example, illustrates that the liquid is blood and the blood is added to the syringe to mix with the dried DBM pellets. In some embodiments, the blood volume comprises from about 3 mL to about 9 mL. In some embodiments, the liquid volume comprises from about 6 cc to about 12 cc, for example as shown in FIG. 12. In some embodiments, an injection force to inject the injectable demineralized bone matrix is from about 10 lbs. to about 33 lbs., from about 15 lbs. to about 33 lbs., or from about 24 lbs. to about 27 lbs. In some embodiments, the hydrated DBM pellets in a syringe, for example as shown in FIG. 11, are tested for handling characteristics through injection force, as shown in FIG. 12. In some embodiments, the injection force decreases as hydration volume ratio in syringe increases. In some embodiments, the graft volume comprises the DMB pellets and the liquid. In some embodiments, the injection force increases as the volume of the hydrated DBM pellets increases.

In some embodiments, the demineralized bone matrix pellet comprises from about 0 wt. % to about 33 wt. %, from about 0.1 wt. % to about 33 wt. %, from about 0.5 wt. % to about 33 wt. %, from about 1 wt. % to about 33 wt. %, from about 5 wt. % to about 33 wt. %, from about 10 wt. % to about 33 wt. %, from about 15 wt. % to about 33 wt. %, from about 20 wt. % to about 33 wt. %, from about 25 wt. % to about 33 wt. %, or from about 30 wt. % to about 33 wt. % short demineralized bone fibers and from about 66 wt. % to about 99.9 wt. %, from about 70 wt. % to about 99.9 wt. %, from about 75 wt. % to about 99.9 wt. %, or from about 80 wt. % to about 99.9 wt. % long demineralized bone fibers based on a total weight of the bone fibers or based on a total weight of the demineralized bone matrix pellet. In some embodiments, the compacting comprises applying pressure to the mixture manually with a spatula or a roller and compression block. In some embodiments, no compression is applied. In some embodiments, the ratio of long demineralized bone fibers to short demineralized bone fibers is from about 100:0 to about 90:10 respectively, about 80:20 respectively, about 70:30 respectively, or about 66:33 respectively, or about 60:40 respectively. In some embodiments, the dried DBM pellets are aseptically packaged into the syringe. In some embodiments, the dried DBM pellets have a diameter ranging from about 7 mm to about 10 mm, from about 7 mm to about 8 mm, from about 8 mm to about 9 mm, from about 9 mm to about 10 mm, from about 7 mm to about 10 mm, or from about 8 mm to about 10 mm. In some embodiments the dried DBM pellets have a height ranging from 2 mm to about to about 4 mm, from about 2 mm to about 3 mm, from about 3 mm to about 4 mm.

In some embodiments, a bone material comprising a mixture of a plurality of long bone fibers having a diameter from about 0.5 mm to about 8.0 mm and a plurality of short bone fibers having a diameter from about 0.5 mm to about 0.05 mm, is provided. In some embodiments, the bone material is demineralized and molded into a lyophilized demineralized bone matrix in pellet form. In some embodiments, the bone material comprises demineralized bone powder having a diameter of about 0.106 mm and below. In some embodiments, the bone material comprises DBM pellets. In some embodiments, the DBM pellets have substantially similar size from about 1 mm to about 15 mm, from about 1 mm to about 3 mm, from about 3 mm to about 6 mm, from about 6 mm to about 10 mm, from about 10 mm to about 15 mm. In some embodiments, each DBM pellet has a microporosity and the diameter of each of the micropores is from about 0.01 to about 10 microns. In some embodiments, the diameter of each of the micropores of the DBM pellet is from about 0.1 to about 10 microns or from about 1 to about 10 microns. In some embodiments, the diameter of each of the micropores can be from about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9 to about 10 microns. In some embodiments, the DBM pellets have a percent microporosity from about 10 to about 100% or from about 10, 20, 30, 40, 50, 60, 70, 80, 90 to about 100%. In some embodiments, DBM pellets have one single substantially similar size, shape and porosity.

In some embodiments, the method includes hydrating the bone material with liquid to an injectable viscosity of from about 50 Pa-s to about 3000 Pa-s. In some embodiments, the demineralized bone powder is from about 15 wt. % to about 33 wt. % based on a total weight of the demineralized bone matrix pellet.

In some embodiments, the demineralized bone matrix pellet comprises from about 0.01 wt. % to about 33 wt. % short demineralized bone fibers and from about 80 wt. % to about 99.99 wt. % long demineralized bone fibers based on a total weight of the bone fibers or based on a total weight of the demineralized bone matrix pellet.

FIG. 9 illustrates an embodiment of a texture analyzer. In some embodiments, the handling characteristics including the handling texture is measured by a texture analyzer. In some embodiments, the DBM pellets are disposed in a texture analyzer to test its handling texture. In some embodiments, the material consistency of the DBM pellets is measured by the injection force. In some embodiments, the DBM pellets are tested for both handling texture and the material consistency.

FIG. 10 illustrates an embodiment of loading the dried DBM fiber pellets 134 into a syringe 136. In some embodiments, the DBM pellets are aseptically packaged into a first chamber comprising a first syringe. The liquid 138, which is disposed in a second chamber comprising a second syringe, is added to the first syringe, as shown in FIG. 11. FIG. 11 also illustrates an embodiment in which the plunger in the first syringe has been moved between a retracted position and an extended position 20 times or 20 pumps. In some embodiments, the first chamber may receive 5, 10, 15, 20 or 30 pumps after the liquid is added to the first chamber. FIG. 12 correlates the hydration of the DBM pellets and the injection force exerted on the DBM pellets.

Bone Material

DBM compositions and methods that allow osteogenesis, osteoinduction and/or osteoconduction are provided. DBM compositions, devices and methods are provided that allow osteogenesis, osteoinduction and/or osteoconduction. The DBM compositions, devices and methods provided, in some embodiments, are made from bone material that does not contain a binder. DBM compositions, devices and methods that easily allow hydration of the demineralized bone matrix are also provided.

Compositions and methods are provided for a bone material for hydration with a liquid, the bone material comprising a DBM pellet of milled and demineralized bone fibers, the DBM pellet of demineralized fiber having no binder disposed in or on the DBM pellet. In some embodiments, the bone material is lyophilized. In some embodiments, the demineralized bone fibers are cartridge milled and have a ribbon-like shape and increased surface area. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers are cartridge milled fibers having a ribbon-like shape, increased surface area and a curled portion. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers comprises autograft or allograft bone. In some embodiments, the bone fibers have a diameter from about 100 μm to about 2 mm. In some embodiments, the bone fibers have a length from about 0.5 mm to about 50 mm. In some embodiments, the bone fibers have an average length from about 0.5 cm to about 10 cm. In some embodiments, the fibers have an aspect ratio of from about 50:1 to about 1000:1, from about 50:1 to about 950:1, from about 50:1 to about 750:1, from about 50:1 to about 500:1, from about 50:1 to about 250:1, from about 50:1 to about 100:1, from about 10:1 to about 50:1, or from about 5:1 to about 10:1. In some embodiments, the liquid for hydration of the fibers comprises blood, water, saline or a combination thereof. In some embodiments, the liquid for hydration of the fibers is mixed with the DBM pellet of milled and demineralized bone fibers that are lyophilized without a binder to form moldable lyophilized demineralized bone fiber.

In some embodiments, the bone fibers have a ribbon like shape and have increased surface area by from about 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, 19.0, 19.5, 20.0, 20.5, 21.0, 21.5, 22.0, 22.5, 23.0, 23.5, 24.0, 24.5, 25.0, 25.5, 26.0, 26.5, 27.0, 27.5, 28.0, 28.5, 29.0, 29.5, 30.0, 30.5, 31.0, 31.5, 32.0, 32.5, 33.0, 33.5, 34.0, 34.5, 35.0, 35.5, 36.0, 36.5, 37.0, 37.5, 38.0, 38.5, 39.0, 39.5, 40.0, 40.5, 41.0, 41.5, 42.0, 42.5, 43.0, 43.5, 44.0, 44.5, 45.0, 45.5, 46.0, 46.5, 47.0, 47.5, 48.0, 48.5, 49.0, 49.5, 50.0, 55.0, 60.0, 65.0, 70.0, 75.0, 80.0, 85.0, 90.0, 95.0, to about 100.0% when compared to bone chips, or powders.

In some embodiments, a device for mixing a bone material with a liquid is provided. The device comprises a chamber having a proximal end and a distal end, and the bone material disposed within the chamber, the bone material comprising a DBM pellet of milled and lyophilized demineralized bone fibers; and a plunger having at least a portion slidably disposed within the proximal end of the chamber and configured to dispense the bone material mixed with liquid from the distal end of the chamber, when the plunger is in an extended position. In some embodiments, the chamber comprises a syringe barrel. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers does not contain a binder. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers comprises cartridge milled fibers having a curled portion. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers comprises autograft or allograft bone. In some embodiments, the bone fibers have a diameter from about 100 μm to about 2 mm. In some embodiments, the bone fibers have a length from about 0.5 mm to about 50 mm. In some embodiments, the bone fibers have an average length from about 0.5 cm to about 10 cm. In some embodiments, the fibers have an aspect ratio of from about 50:1 to about 1000:1, from about 50:1 to about 950:1, from about 50:1 to about 750:1, from about 50:1 to about 500:1, from about 50:1 to about 250:1, from about 50:1 to about 100:1, from about 10:1 to about 50:1, or from about 5:1 to about 10:1. In some embodiments, the liquid for hydration of the fibers comprises blood, water, saline or a combination thereof. In some embodiments, the liquid is mixed lyophilized demineralized bone fibers to form moldable lyophilized demineralized bone fiber. In some embodiments, the liquid is mixed with the lyophilized demineralized bone fibers using negative pressure created in the chamber by the plunger. In some embodiments, the distal end of the chamber comprises a removable cap.

In some embodiments, a method for hydrating a bone material with a liquid is provided. The method comprises mixing the liquid with the bone material comprising a DBM pellet of milled and lyophilized demineralized bone fibers in a device comprising a first chamber having a proximal end and a distal end, and the bone material disposed within the first chamber; and a first plunger having at least a portion slidably disposed within the proximal end of the first chamber; a second chamber having a proximal end and a distal end, and the liquid disposed within the second chamber, the liquid configured to hydrate the DBM pellet of milled and lyophilized demineralized bone fibers; and a second plunger having at least a portion slidably disposed within the proximal end of the second chamber; a connector fluidly coupling the distal end of the first chamber to the distal end of the second chamber, wherein movement of the second plunger to an extended position causes liquid to flow to hydrate the DBM pellet of milled and lyophilized demineralized bone fibers in the first chamber.

Compositions and methods are provided for a bone material comprising a DBM pellet of cartridge milled and demineralized bone fibers, the DBM pellet of cartridge milled and demineralized bone fibers having no binder disposed in or on the DBM pellet. In some embodiments, the bone material comprises cortical bone, cancellous bone, cortico-cancellous bone, or mixtures thereof. In some embodiments, the bone material is obtained from autogenous bone, allogeneic bone, xenogeneic bone, or mixtures thereof. In some embodiments, the DBM pellet is lyophilized and shaped. In some embodiments, the shape of the lyophilized DBM pellet is cube-, square-, triangle-, rectangular-, circular-, disc- or cylinder-shaped. In some embodiments, the shape of the lyophilized DBM pellet is disc-shaped and the disc has a reservoir configured to contact a liquid. In some embodiments, the shape of the lyophilized DBM pellet is cylinder-shaped. In some embodiments, the DBM pellet has a plurality of channels running longitudinally through the center of the cylinder-shaped bone material to allow fluid to hydrate the bone material. In some embodiments, the DBM pellet has a plurality of channels running longitudinally through the exterior of the cylinder-shaped bone material to allow fluid to hydrate the bone material. In some embodiments, the cylinder-shaped bone material further comprises a plurality of channels running longitudinally through an exterior of the bone material to allow fluid to hydrate the bone material.

Compositions and methods are provided for an implantable bone graft comprising fibers obtained from allograft bone, the fibers comprising hooking portions configured to interlock with one another to form a DBM pellet, wherein the composition does not include a binding agent.

Typically, when bone is processed into particles or fibers, it is statically charged and not coherent or adherent. The processed bone is normally contained within an external structure (i.e., a bag or covering) or mixed with a carrier or binding agent to provide a cohesive structure. When implanted, this external structure or carrier must be removed by the patient's body, potentially impacting the osteoinductive potential of the graft.

In some embodiments, a DBM pellet of bone fibers without additional carrier contains bone processed in such a way that it provides for cohesion between fibers without additional containment or binding agents is provided. Bone shafts are milled to create curled bone fibers which are subsequently demineralized and freeze-dried. The fiber shape is altered during the drying process, which leads to physical entanglement and surface-to-surface interactions between adjacent fibers. The entanglement/interaction of the fibers is responsible for the cohesiveness of the final product. Thus, the present disclosure provides for a fibrous bone material having a size and shape that provides for increased surface area and the ability to mechanically interlock with one another to form an implantable DBM pellet.

The compositions of the present disclosure results are utilized in an effective bone grafting product. The bone graft material is resorbed/remodeled and replaced by host bone during the healing process. In some embodiments, the bone material disclosed herein includes additional additives, such as synthetic ceramics and/or bioerodible polymers, which produce high concentrations of calcium, phosphate and silicon ions that act as a nidus for de novo bone formation, as discussed herein. As the bioerodible polymer degrades faster than the ceramic, more and more osteoinductive DBM particles are exposed. The slower resorbing ceramic may act as a solid surface for stem cells and osteoblasts to attach to and begin laying down new bone.

The DBM pellet of the disclosure has good flexibility and is compression resistant. It is also osteoinductive with the demineralized bone matrix retaining activity. These properties make an excellent bone graft substitute in that it may not break, crack, or deform when implanted in the body.

The implantable composition may be a combination of fibers of bone matrix from allograft bone and fibers of non-allograft bone material. The fibers of the non-allograft bone material comprise non-fibrous demineralized bone matrix particles embedded within or dispersed on the fibers of the non-allograft bone material. The ratio of fibers of demineralized bone matrix from allograft material to fibers of non-allograft material ranges from about 20:80 to about 70:30. In one embodiment, the ratio of fibers from allograft material to fibers of non-allograft material ranges from about 40:60 to about 60:40. In one embodiment, the ratio of fibers of demineralized bone matrix from allograft material to fibers of non-allograft material is about 50:50.

In some embodiments, the demineralized bone material includes particles that are non-fibrous. In some embodiments, the particles are powders, microspheres, sponges, pastes, gels, and/or granules. In one embodiment, the particles are powders.

In some embodiments, the demineralized bone material fibers comprise from about 1 to about 70 micrometers or from about 125 to about 250 micrometers. In some embodiments, the demineralized bone material fibers comprise about 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 152, 154, 156, 158, 160, 162, 164, 166, 168, 170, 172, 174, 176, 178, 180, 182, 184, 186, 188, 190, 192, 194, 196, 198, 200, 202, 204, 206, 208, 210, 212, 214, 216, 218, 220, 222, 224, 226, 228, 230, 232, 234, 236, 238, 240, 242, 244, 246, 248 and/or 250 micrometers. In some embodiments, the bone fibers include a length from about 100 micrometers to about 2 mm. In some embodiments, the bone fibers have a length from about 0.5 cm to about 10 cm, about 1 cm to about 8 cm, about 3 cm to about 5 cm, about 0.5 mm to about 50 mm, about 1.0 mm to about 25 mm, or about 5 mm to about 10 mm. The fibers include a diameter of about 100 micrometers to about 4 mm.

The fibers are milled in such a way as to provide increased surface area in a compact shape and size. In some embodiments, the fibers include a curled shape such that diameter of the curled fibers is between about 50 micrometers and about 3 mm, and the diameter of the fibers in a flattened configuration is about 125 micrometers to about 5 mm. In some embodiments, the fibers include a curled shape such that diameter of the curled fibers is between about 100 micrometers and about 1 mm, and the diameter of the fibers in a flattened configuration is about 250 micrometers to about 2 mm.

In various embodiments, the fibers have an aspect ratio of length to width from about 50:1 to about 1000:1, from about 50:1 to about 950:1, from about 50:1 to about 750:1, from about 50:1 to about 500:1, from about 50:1 to about 250:1, from about 50:1 to about 100:1, from about 10:1 to about 50:1, or from about 5:1 to about 10:1. In other embodiments, the fibers have an aspect ratio of length to width of about 4:1, 17:1, or 23:1.

The composition has very low immunogenicity and good compatibility to fill a bone void.

In general, advantageous, osteoinductive DBM materials can be prepared by decalcification of cortical and/or cancellous bone fibers, often by acid extraction. The fibers can be milled, for example, cartridge milled. The acid extraction process can be conducted so as to leave collagen, noncollagenous proteins, and growth factors together in a solid fiber. Methods for preparing bioactive demineralized bone are described in U.S. Pat. Nos. 5,073,373; 5,484,601; and 5,284,655, as examples. DBM products are also available commercially, including, for instance, from sources such as Regeneration Technologies, Inc. (Alachua, Fla.), The American Red Cross (Arlington, Va.), and others. Bone fibers that are solely osteoconductive can be prepared using similar techniques that have been modified or supplemented to remove or inactivate (e.g. by crosslinking or otherwise denaturing) components in the bone matrix responsible for osteoinductivity. Osteoinductive and/or osteoconductive DBM materials used in the present disclosure can be derived from human donor tissue, especially in regard to implant devices intended for use in human subjects.

In regard to the fiber content of the DBM pellet on a dry weight basis, the bone fiber material can constitute about 5% to about 100% of the compositions, about 20% to about 80%, or about 25% to about 75% by weight.

In some embodiments, the bone fibers of allograft bone have an average length to average thickness ratio or aspect ratio of the fibers from about 50:1 to about 1000:1. In overall appearance, the bone fibers can be in the form of ribbons, threads, narrow strips, and/or thin sheets. The elongated bone fibers can be substantially linear in appearance or they can be coiled to resemble springs. In some embodiments, the bone fibers have linear portions and coiled portions. In some embodiments, the bone fibers are of irregular shapes including, for example, linear, serpentine and/or curved shapes. In some embodiments, the fibers can be curled at the edges to have a substantially hemicircular cross-sections. In some embodiments, the fibers may be entirely or partially helical, circumvoluted or in the shape of a corkscrew. The elongated bone fibers can be demineralized however some of the original mineral content may be retained when desirable for a particular embodiment. The bone graft fiber may further comprise mineralized bone material.

The bone fibers are elongated and curled to increase the surface area of the strips. The curled fibers may include frayed portions along the edges to facilitate interactions with other bone fibers. In some embodiments, the curled fibers are milled to have hooked portions along the edges of the fibers configured to engage with other fibers. The hooked portions may engage other hooked portions, frayed portions, straightened portions or curled portions of other fibers. The hooked and frayed portions and the curled shape of the fibers provide for entanglement between fibers such that the fibers form a DBM pellet without the need for a carrier or binding agent.

The bone fiber sizes and shapes may be created in a number of ways, for example, through cartridge milling. One such example of a suitable cartridge mill is the Osteobiologic Milling Machine, as described in U.S. Patent Publication No. 2012/0160945, assigned to Warsaw Orthopedic, Inc. and is hereby incorporated by reference in its entirety. However, it is contemplated that the bone fibers may be alternatively milled using vices, cutters, rollers, rotating rasps or reciprocating blade mills.

In some embodiments, the bone material may be combined with non-bone material additives after demineralization and/or lyophilization and before implantation. For example, the bone material may be combined with a bioerodible polymer. The bioerodible polymer exhibits dissolution when placed in a mammalian body and may be hydrophilic (e.g., collagen, hyaluronic acid, polyethylene glycol). Synthetic polymers are suitable according to the present disclosure, as they are biocompatible and available in a range of copolymer ratios to control their degradation.

In some embodiments, hydrophobic polymers (e.g. poly(lactide-co-glycolyde), polyanhydrides) may be used. Alternatively, a combination of hydrophilic and hydrophobic polymers may be used in the bone graft composition of the disclosure.

Exemplary materials may include biopolymers and synthetic polymers such as human skin, human hair, bone, collagen, fat, thin cross-linked sheets containing fibers and/or fibers and chips, polyethylene glycol (PEG), chitosan, alginate sheets, cellulose sheets, hyaluronic acid sheet, as well as copolymer blends of poly (lactide-co-glycolide) PLGA.

In some embodiments, the particles disclosed herein can also include other biocompatible and bioresorbable substances. These materials may include, for example, natural polymers such as proteins and polypeptides, glycosaminoglycans, proteoglycans, elastin, hyaluronic acid, dermatan sulfate, gelatin, or mixtures or composites thereof. Synthetic polymers may also be incorporated into the bone graft composites. These include, for example biodegradable synthetic polymers such as polylactic acid, polyglycolide, polylactic polyglycolic acid copolymers (“PLGA”), polycaprolactone (“PCL”), poly(dioxanone), poly(trimethylene carbonate) copolymers, polyglyconate, poly(propylene fumarate), poly(ethylene terephthalate), poly(butylene terephthalate), polyethylene glycol, polycaprolactone copolymers, polyhydroxybutyrate, polyhydroxyvalerate, tyrosine-derived polycarbonates and any random or (multi-)block copolymers, such as bipolymer, terpolymer, quaterpolymer, etc., that can be polymerized from the monomers related to previously-listed homo- and copolymers.

The bioerodible polymer may have a molecular weight of from about 1,000 to about 30,000 Daltons (Da). In various embodiments, the polymer may have a molecular weight of from about 2,000 to about 10,000 Da. In some embodiments, the polymer may have a molecular weight of from about 2,000 to 4,000 Da or from about 3,000 to 4,000 Da. In some embodiments, the bioerodible polymer may have a molecular weight of 1,000, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, 20,000, 21,000, 22,000, 23,000, 24,000, 25,000, 26,000, 27,000, 28,000, 29,000 or about 30,000 Da.

In some embodiments, the bioerodible polymer is collagen. Collagen has excellent histocompatibility without antibody formation or graft rejection. Any suitable collagen material may be used, including known collagen materials, or collagen materials as disclosed in U.S. patent application Ser. No. 12/030,181, filed Feb. 12, 2008, hereby incorporated by reference in its entirety. Various collagen materials can be used, alone or in combination with other materials.

Insoluble collagen material for use in the disclosure can be derived from natural tissue sources, (e.g. xenogeneic, allogeneic, or autogenic relative to the recipient human or other patient) or recombinantly prepared. Collagens can be subclassified into several different types depending upon their amino acid sequence, carbohydrate content and the presence or absence of disulfide crosslinks. Types I and III collagen are two of the most common subtypes of collagen and may be used in the present disclosure. Type I collagen is present in skin, tendon and bone, whereas Type III collagen is found primarily in skin. The collagen used in compositions of the disclosure can be obtained from skin, bone, tendon, or cartilage and purified by methods well known in the art and industry. Alternatively, the collagen can be purchased from commercial sources.

The collagen can be atelopeptide collagen and/or telopeptide collagen. Still further, either or both of non-fibrillar and fibrillar collagen can be used. Non-fibrillar collagen is collagen that has been solubilized and has not been reconstituted into its native fibrillar form.

Suitable collagen products are available commercially, including for example from Kensey Nash Corporation (Exton, Pa.), which manufactures a fibrous collagen known as Semed F, from bovine hides. Collagen materials derived from bovine hide are also manufactured by Integra Life Science Holding Corporation (Plainsboro, N.J.). Naturally-derived or recombinant human collagen materials are also suitable for use in the disclosure. Illustratively, recombinant human collagen products are available from Fibrogen, Inc. (San Francisco, Calif.).

In some embodiments, the fibers can be combined with synthetic ceramics that are effective to provide a scaffold for bone growth and which are completely bioresorbable and biocompatible. The synthetic ceramics should provide high local concentrations of calcium, phosphate and silicon ions that act as a nidus for de-novo bone formation. The use of such a resorbable ceramics provides many advantages over alternative conventional materials. For instance, it eliminates the need for post-therapy surgery for removal and degrades in the human body to biocompatible, bioresorbable products.

In some embodiments, the synthetic ceramics disclosed herein may be selected from one or more materials comprising calcium phosphate ceramics or silicon ceramics. Biological glasses such as calcium-silicate-based bioglass, silicon calcium phosphate, tricalcium phosphate (TCP), biphasic calcium phosphate, calcium sulfate, hydroxyapatite, coralline hydroxyapatite, silicon carbide, silicon nitride (Si₃N₄), and biocompatible ceramics may be used. In some embodiments, the ceramic is tri-calcium phosphate or biphasic calcium phosphate and silicon ceramics. In some embodiments, the ceramic is tricalcium phosphate.

In some embodiments, the ceramics are a combination of a calcium phosphate ceramic and a silicon ceramic. In some embodiments, the calcium phosphate ceramic is resorbable biphasic calcium phosphate (BCP) or resorbable tri-calcium phosphate (TCP), most preferably resorbable TCP.

Biphasic calcium phosphate can have a tricalcium phosphate:hydroxyapatite weight ratio of about 50:50 to about 95:5, about 70:30 to about 95:5, about 80:20 to about 90:10, or about 85:15. The mineral material can be a granular particulate having an average particle diameter between about 0.2 and 5.0 mm, between about 0.4 and 3.0 mm, or between about 0.4 and 2.0 mm.

The ceramics of the disclosure may also be oxide ceramics such as alumina (Al₂O₃) or zirconia (ZrO₂) or composite combinations of oxides and non-oxides such as silicon nitride).

In some embodiments, after the DBM pellet of DBM fibers is formed, a binding agent may be added to it before implantation. However, in some embodiments, the DBM pellet of DBM fibers does not contain a binding agent and is stays together without the use of a binding agent. Examples of suitable binding agents that optionally can be included after the DBM pellet is formed include, but are not limited to: (i) Polyhydroxy compound, for example, such classes of compounds as the acyclic polyhydric alcohols, non-reducing sugars, sugar alcohols, sugar acids, monosaccarides, disaccharides, water-soluble or water dispersible oligosaccarides, polysaccarides and known derivatives of the foregoing. Specific polyhydroxy compounds include, 1,2-propanediol, glycerol, 1,4,-butylene glycol trimethylolethane, trimethylolpropane, erythritol, pentaerythritol, ethylene glycols, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol; polyoxyethylene-polyoxypropylene copolymer, for example, of the type known and commercially available under the trade names Pluronic and Emkalyx; polyoxyethylene-polyoxypropylene block copolymer, for example, of the type known and commercially available under the trade name Poloxamer; alkylphenolhydroxypolyoxyethylene, for example, of the type known and commercially available under the trade name Triton, polyoxyalkylene glycols such as the polyethylene glycols, xylitol, sorbitol, mannitol, dulcitol, arabinose, xylose, ribose, adonitol, arabitol, inositol, fructose, galactose, glucose, mannose, sorbose, sucrose, maltose, lactose, maltitol, lactitol, stachyose, maltopentaose, cyclomaltohexaose, carrageenan, agar, dextran, alginic acid, guar gum, gum tragacanth, locust bean gum, gum arabic, xanthan gum, amylose, mixtures of any of the foregoing.

The carrier or binding agent may further comprise a hydrogel such as hyaluronic acid, dextran, pluronic block copolymers of polyethylene oxide and polypropylene, and others. Suitable polyhodroxy compounds include such classes of compounds as acyclic polyhydric alcohols, non-reducing sugars, sugar alcohols, sugar acids, monosaccharides, disaccharides, water-soluble or water dispersible oligosaccharides, polysaccharides and known derivatives of the foregoing. An example carrier comprises glyceryl monolaurate dissolved in glycerol or a 4:1 to 1:4 weight mixture of glycerol and propylene glycol. Settable materials may be used, and they may set up either in situ, or prior to implantation. Optionally, xenogeneic bone powder carriers also may be treated with proteases such as trypsin. Xenogeneic carriers may be treated with one or more fibril modifying agents to increase the intraparticle intrusion volume (porosity) and surface area. Useful agents include solvents such as dichloromethane, trichloroacetic acid, acetonitrile and acids such as trifluoroacetic acid and hydrogen fluoride. The choice of carrier may depend on the desired characteristics of the composition. In some embodiments, a lubricant, such as water, glycerol, or polyethylene glycol may be added.

In some embodiments, the composition containing the fibers may also contain other beneficial substances including for example preservatives, cosolvents, suspending agents, viscosity enhancing agents, ionic strength and osmolality adjusters and/or other excipients. Suitable buffering agents can also be used an include but are not limited to alkaline earth metal carbonates, phosphates, bicarbonates, citrates, borates, acetates, succinates, or others. Illustrative-specific buffering agents include for instance sodium phosphate, sodium citrate, sodium borate, sodium acetate, sodium bicarbonate, sodium carbonate, and sodium tromethanine (TRIS).

In some embodiments, the DBM pellet of bone fibers may be mixed with a porogen material which is later removed during manufacturing to enhance porosity of the dried DBM pellet. Suitable porogen materials may be made of any biocompatible, biodegradable substance that can be formed into a particle and that is capable of at least substantially retaining its shape during the manufacturing of the implant but is later removed or degrades or dissolves when placed in contact with an aqueous solution, or other liquid. The porogens, in some embodiments, may be inorganic or organic, for example, they may be made from gelatin, an organic polymer (e.g., polyvinyl alcohol), polyurethanes, polyorthoesters, PLA, PGA, and PLGA copolymers, a saccharide, a calcium salt, sodium chloride, calcium phosphate or mixtures thereof. Porogen particles may be about 100 to about 500 microns.

In one embodiment, all porogen particles of a given morphology can have at least one average axial, transverse, or lateral dimension that is about 100 to about 500 microns. In some embodiments, all porogen particles used can independently have at least one axial, transverse, or lateral dimension that is about 100 to about 500 microns. In some embodiments, all porogen particles used can collectively have at least one average axial, transverse, or lateral dimension that is about 100 to about 500 microns. In some embodiments, at least one dimension of the porogen particles can be about 100 microns or more, or about 120 microns or more, or about 140 microns or more. In some embodiments, at least one dimension of the porogen particles can be about 500 microns or less, about 425 microns or less, about 350 microns or less, about 300 microns or less, or about 250 microns or less. In some embodiments, the porogen particles can have at least one dimension that is about 120 to about 400 microns.

In some embodiments the DBM pellet of fibers could contain single or multiple concentrations of size controlled fibers to affect the consistency of the DBM pellet and affect the handling of the mass after hydration.

In some instances, fibers maybe mixed with particles in the DBM pellet to affect the consistency of the DBM pellet and affect the handling of the mass after hydration.

In some instances, multiple DBM pellets might be packaged together to improve hydration and/or handling of the DBM pellets prior to and after hydration.

In some instances, the DBM pellets may be hydrated with a polar or non-polar solutions and/or salt solutions prior to drying to enhance later rehydration of the mass.

One of more biologically active ingredients may be added to the resulting composition (e.g., lyophilized bone fibers). These active ingredients may or may not be related to the bone repair capabilities of the composition. Suitable active ingredients hemostatic agents, bone morphogenic proteins (BMPs), genes, growth differentiation factors (GDFs), or other non-collagenic proteins such as TGF-β, PDGF, osteopontin, osteonectin, cytokines, and the like.

In one embodiment, the composition may include at least one BMPs, which are a class of proteins thought to have osteoinductive or growth-promoting activities on endogenous bone tissue, or function as pro-collagen precursors. Known members of the BMP family include, but are not limited to, BMP-1, BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7, BMP-8, BMP-9, BMP-10, BMP-11, BMP-12, BMP-13, BMP-15, BMP-16, BMP-17, BMP-18 as well as polynucleotides or polypeptides thereof, as well as mature polypeptides or polynucleotides encoding the same.

BMPs utilized as osteoinductive agents comprise one or more of BMP-1; BMP-2; BMP-3; BMP-4; BMP-5; BMP-6; BMP-7; BMP-8; BMP-9; BMP-10; BMP-11; BMP-12; BMP-13; BMP-15; BMP-16; BMP-17; or BMP-18; as well as any combination of one or more of these BMPs, including full length BMPs or fragments thereof, or combinations thereof, either as polypeptides or polynucleotides encoding the polypeptide fragments of all of the recited BMPs. The isolated BMP osteoinductive agents may be administered as polynucleotides, polypeptides, full length protein or combinations thereof.

In another embodiment, the particles may include one or more Growth Differentiation Factors (“GDFs”) disposed in the compartment or disposed on or in the DBM pellet. Known GDFs include, but are not limited to, GDF-1, GDF-2, GDF-3, GDF-7, GDF-10, GDF-11, and GDF-15. For example, GDFs useful as isolated osteoinductive agents include, but are not limited to, the following GDFs: GDF-1 polynucleotides or polypeptides corresponding to GenBank Accession Numbers M62302, AAA58501, and AAB94786, as well as mature GDF-1 polypeptides or polynucleotides encoding the same. GDF-2 polynucleotides or polypeptides corresponding to GenBank Accession Numbers BC069643, BC074921, Q9UK05, AAH69643, or AAH74921, as well as mature GDF-2 polypeptides or polynucleotides encoding the same. GDF-3 polynucleotides or polypeptides corresponding to GenBank Accession Numbers AF263538, BC030959, AAF91389, AAQ89234, or Q9NR23, as well as mature GDF-3 polypeptides or polynucleotides encoding the same. GDF-7 polynucleotides or polypeptides corresponding to GenBank Accession Numbers AB158468, AF522369, AAP97720, or Q7Z4P5, as well as mature GDF-7 polypeptides or polynucleotides encoding the same. GDF-10 polynucleotides or polypeptides corresponding to GenBank Accession Numbers BC028237 or AAH28237, as well as mature GDF-10 polypeptides or polynucleotides encoding the same.

GDF-11 polynucleotides or polypeptides corresponding to GenBank Accession Numbers AF100907, NP005802 or 095390, as well as mature GDF-11 polypeptides or polynucleotides encoding the same. GDF-15 polynucleotides or polypeptides corresponding to GenBank Accession Numbers BC008962, BC000529, AAH00529, or NP004855, as well as mature GDF-15 polypeptides or polynucleotides encoding the same.

In some embodiments, the implantable composition contains other bioactive agents which can be delivered with materials of the disclosure. In certain embodiments, the bioactive agent is a drug. These bioactive agents may include, for example, antimicrobials, antibiotics, antimycobacterial, antifungals, antivirals, antineoplastic agents, antitumor agents, agents affecting the immune response, blood calcium regulators, agents useful in glucose regulation, anticoagulants, antithrombotics, antihyperlipidemic agents, cardiac drugs, thyromimetic and antithyroid drugs, adrenergics, antihypertensive agents, cholinergic, anticholinergics, antispasmodics, antiulcer agents, skeletal and smooth muscle relaxants, prostaglandins, general inhibitors of the allergic response, antihistamines, local anesthetics, analgesics, narcotic antagonists, antitussives, sedative-hypnotic agents, anticonvulsants, antipsychotics, anti-anxiety agents, antidepressant agents, anorexigenics, non-steroidal anti-inflammatory agents, steroidal anti-inflammatory agents, antioxidants, vaso-active agents, bone-active agents, osteogenic factors, antiarthritics, and diagnostic agents.

A more complete listing of bioactive agents and specific drugs suitable for use in the present disclosure may be found in “The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals,” Edited by Susan Budavari, et al.; and the United States Pharmacopoeia/National Formulary XXXVII/XXXII, published by the United States Pharmacopeial Convention, Inc., Rockville, Md., 2013, each of which is incorporated herein by reference.

Bioactive agents may also be provided by incorporation into the implantable composition. Bioactive agents such as those described herein can be incorporated homogeneously or regionally into the implant material by simple admixture or otherwise. Further, they may be incorporated alone or in conjunction with another carrier form or medium such as microspheres or another microparticulate formulation. Suitable techniques for forming microparticles are well known in the art and can be used to entrain or encapsulate bioactive agents, whereafter the microparticles can be dispersed within the bone graft composite upon or after its preparation.

It will be appreciated that the amount of additive used will vary depending upon the type of additive, the specific activity of the particular additive preparation employed, and the intended use of the composition. The desired amount is readily determinable by the user.

Any of a variety of medically and/or surgically useful substances can be incorporated in, or associated with, the allograft bone material either before, during, or after preparation of the implantable composition. Thus, for example when the non-allograft bone material is used, one or more of such substances may be introduced into the bone fibers, for example, by soaking or immersing these bone fibers in a solution or dispersion of the desired substance(s).

In some embodiments, the DBM pellet of fibers can be lyophilized with one or more growth factors (e.g., BMP, GDF, etc.), drugs so that it can be released from the DBM pellet it in a sustained release manner.

Bone Fiber Shapes

The bone fibers can be obtained from bone that is cortical, cancellous or cortico-cancellous of autogenous, allogeneic, xenogeneic, or transgenic origin. This bone can be cartridge milled to obtain the bone fibers of the desired size and diameter. Suitable cartridge mills that can be used to obtain the fibers of desired size and diameter can be obtained from the cartridge mills described in U.S. patent Ser. No. 13/333,279, filed on Dec. 21, 2011 and entitled “OSTEOBIOLOGIC MILLING MACHINE”, which was published as U.S. Publication No. 20120160945. This entire disclosure is herein incorporated by reference into the present disclosure, particularly FIG. 2. The milling apparatus described in U.S. Publication No. 20120160945 has a cutter housing and feed chute, a rotary cutter, at least partially housed within the cutter housing and in communication with the feed chute, and a feed ram removably positioned within the feed chute for maintaining a workpiece against the rotary cutter. The feed chute and feed ram may be selectively positionable at one of several angular positions with respect to the rotary cutter. In this manner, the force applied by the feed ram on the workpiece is a function of the weight of the feed ram and the angular position of the feed ram with respect to the rotary cutter. These type of bone milling machines and methods of use result in up to about one-hundred percent (about 100%) workpiece utilization. That is, the bone milling machines described in U.S. Publication No. 20120160945 use the majority of the bone that is placed in the machine and up to one-hundred percent can be used. After milling the bone to the desired fiber size and shape, the bone fiber obtain can subsequently be demineralized.

In some embodiments, the fibers are milled from bone shafts using any appropriate apparatus, such as a cartridge mill. The fibers are milled to include curled shapes having frayed portions and/or hooked portions to facilitate mechanical interlocking of the fibers. For example, milling the bone material creates fibers and bone particles separate from the fiber. The shape of the allograft may be tailored to fit the site at which it is to be situated. For example, it may be in the shape of a morsel, a plug, a pin, a peg, a cylinder, a block, a wedge, ring, a sheet, etc.

In one embodiment, the method comprises placing allograft bone fibers into a mold prior to demineralization and/or lyophilization. The fibers are then demineralized, sterilized and/or lyophilized to create a shaped DBM pellet of fibers. The fibers can be placed into a mold and then subjected to demineralization and/or lyophilization to make the desired shape or the fibers can be demineralization and/or lyophilization and then shaped by stamping or punching the desired shape. The demineralization and lyophilization steps alter the shape of the fibers to facilitate entanglement and mechanical interlocking, as discussed herein. Thus, in some embodiments, the fibers are shaped into a DBM pellet through being subjected to demineralization and/or lyophilization while in a molded cavity (not shown). The fibers form such a DBM pellet without the use of a binding agent or carrier.

In some embodiments, the fibers are placed into molds and shaped to form a DBM pellet in a range of predetermined shapes and sizes according to the needs of a medical procedure. In some embodiments, the allograft may be made by injection molding, compression molding, die pressing, slip casting, laser cutting, water-jet machining, sand casting, shell mold casting, lost tissue scaffold casting, plaster-mold casting, vacuum casting, permanent-mold casting, slush casting, pressure casting, die casting, centrifugal casting, squeeze casting, rolling, forging, swaging, extrusion, shearing, spinning, or combinations thereof.

The fibers may be molded into a disc shaped DBM pellet having a reservoir to facilitate hydration. DBM pellet may include a uniform thickness or a variable thickness across its surface to facilitate packaging and/or hydration. Reservoir comprises a depressed area on a surface of DBM pellet to hold liquid during hydration. Reservoir comprises a circular shape. However, in other embodiments, the reservoir may include variable cross sectional shapes, such as polygonal, oval or irregular. In some embodiments, the fibers maybe molded into a conical, plug, cubic, or cylindrical shape. The fibers may be molded into a conical or plug shape to form a DBM pellet. DBM pellet includes a first end having a first diameter and a second end having a second diameter. In some embodiments, the first diameter is wider than the second diameter. The fibers may be molded into a cube shape to form a DBM pellet. In other embodiments, the DBM pellet may include other prismatic configurations, similar to DBM pellet. For example, the DBM pellet may be rectangular, pyramidal, triangular, pentagonal, or other polygonal or irregular prismatic shapes.

Demineralization

After the bone is obtained from the donor and milled into a fiber, it is processed, e.g., cleaned, disinfected, defatted, etc., using methods well known in the art. The entire bone can then be demineralized or, if desired, the bone can just be sectioned before demineralization. The entire bone or one or more of its sections is then subjected to demineralization in order to reduce the inorganic content to a low level, e.g., to contain less than about 10% by weight, preferably less than about 5% by weight and more preferably less than about 1% by weight, residual calcium.

DBM may be prepared in any suitable manner. In one embodiment, the DBM is prepared through the acid extraction of minerals from bone. It includes the collagen matrix of the bone together with acid insoluble proteins including bone morphogenic proteins (BMPs) and other growth factors. It can be formulated for use as granules, gels, sponge material, putty, or paste and can be freeze-dried for storage. Sterilization procedures used to protect from disease transmission may reduce the activity of beneficial growth factors in the DBM. DBM provides an initial osteoconductive matrix and exhibits a degree of osteoinductive potential, inducing the infiltration and differentiation of osteoprogenitor cells from the surrounding tissues. As noted, in embodiments of bone particles taken from cortical long bones, the osteoinductive potential of the bone particles when demineralized may vary based on the source of the bone particles, whether from the periosteal layer, the middle layer, or the endosteal layer.

DBM preparations have been used for many years in orthopedic medicine to promote the formation of bone. For example, DBM has found use in the repair of fractures, in the fusion of vertebrae, in joint replacement surgery, and in treating bone destruction due to underlying disease such as rheumatoid arthritis. DBM is thought to promote bone formation in vivo by osteoconductive and osteoinductive processes. The osteoinductive effect of implanted DBM compositions is thought to result from the presence of active growth factors present on the isolated collagen-based matrix. These factors include members of the TGF-β, IGF, and BMP protein families. Particular examples of osteoinductive factors include TGF-β, IGF-1, IGF-2, BMP-2, BMP-7, parathyroid hormone (PTH), and angiogenic factors. Other osteoinductive factors such as osteocalcin and osteopontin are also likely to be present in DBM preparations as well. There are also likely to be other unnamed or undiscovered osteoinductive factors present in DBM.

In one demineralization procedure, the mixed long bone fibers and short bone fibers are subjected to an acid demineralization step followed by a defatting/disinfecting step, where the DBM pellet of bone fiber can be formed. The bone is immersed in acid to effect demineralization. Acids that can be employed in this step include inorganic acids such as hydrochloric acid and as well as organic acids such as formic acid, acetic acid, peracetic acid, citric acid, propionic acid, etc. The depth of demineralization into the bone surface can be controlled by adjusting the treatment time, temperature of the demineralizing solution, concentration of the demineralizing solution, and agitation intensity during treatment. Thus, in various embodiments, the DBM may be fully demineralized, partially demineralized, or surface demineralized.

The demineralized bone is rinsed with sterile water and/or buffered solution(s) to remove residual amounts of acid and thereby raise the pH. A suitable defatting/disinfectant solution is an aqueous solution of ethanol, the ethanol being a good solvent for lipids and the water being a good hydrophilic carrier to enable the solution to penetrate more deeply into the bone particles. The aqueous ethanol solution also disinfects the bone by killing vegetative microorganisms and viruses. Ordinarily, at least about 10 to 40 percent by weight of water (i.e., about 60 to 90 weight percent of defatting agent such as alcohol) is present in the defatting disinfecting solution to produce optimal lipid removal and disinfection within a given period of time. A suitable concentration range of the defatting solution is from about 60 to about 85 weight percent alcohol, or about 70 weight percent alcohol.

In some embodiments, the demineralized bone may be further treated to effect properties of the bone. For example, the DBM may be treated to disrupt the collagen structure of the DBM. Such treatment may comprise collagenase treatment, heat treatment, mechanical treatment, or other. Reference is made to U.S. Provisional Patent Applications 60/944,408, 60/944,417, and 60/957,614, herein incorporated by reference, for further treatment options.

Lyophilization

The bone fibers can be lyophilized either in a mold for a desired shape or out of a mold, where in can be shaped (e.g., stamped, punched, cut, etc.). For example, the bottle containing bone and conserving agent is initially frozen to −76° C. with the bone and conserving agent later being subjected to a vacuum of less than 100 militorr while the temperature is maintained at or below −35° C. The end point of the lyophilization procedure is the determination of residual moisture of approximately 5%. Once the bone has been lyophilized, it is stored in sealed, vacuum-contained, bottles prior to its reconstitution and use.

In some embodiments, the demineralization and lyophilization steps alter the shape of the fibers to facilitate entanglement and mechanical interlocking. Thus, in some embodiments, the fibers are shaped into a DBM pellet through being subjected to demineralization and/or lyophilization while in a molded cavity (not shown). The fibers form such a DBM pellet without the use of a binding agent or carrier.

To facilitate on-site preparation and/or usage of the composition herein, the demineralized fibrous bone elements and non-fibrous bone elements, preferably in lyophilized or frozen form, and fluid carrier (the latter containing one or more optional ingredients such as those identified above) can be stored in separate packages or containers under sterile conditions and brought together in intimate admixture at the moment of use for immediate application to an osseous defect site employing any suitable means such as spatula, forceps, syringe, tamping device, and the like. Alternatively, the implant composition can be prepared well in advance and stored under sterile conditions until required for use. When the implant composition is prepared well in advance it is preferably lyophilized prior to packaging for storage. In some embodiments, the composition described herein can be combined with autograft bone marrow aspirate, autograft bone, preparations of selected autograft cells, autograft cells containing genes encoding bone promoting action prior to being placed in a defect site. In various embodiments, the implant composition is packaged already mixed and ready for use in a suitable container, such as for example, syringe, resealable non-toxic bottle, a bag mesh or pouch or is provided as a kit which can be prepared at a surgeon's direction when needed.

Hydration

The DBM pellets made from the combination of short fibers and long fibers are hydrophilic and have the desired porosity to be conveniently hydrated into an injectable composition.

In some embodiments, the DBM pellet is hydrated with a liquid comprising bone marrow aspirate, saline, sterile water, blood for injection, phosphate buffered saline, dextrose, Ringer's lactated solution, or a combination thereof. Once hydrated, the hydrated DBM pellet has a flowable consistency to be injected at a bone void location determined by a medical practitioner. The fibers in the hydrated DBM bone material maintain their coherency and mechanical interactions so as to not require a binding agent or carrier when placed in situ. In some embodiments, the DBM pellet can be hydrated to a putty or paste form and administered to the bone void.

In some embodiments, the bone repair composition is hydrated with a physiologically acceptable liquid and biocompatible carrier. Non-limiting examples of physiologically acceptable liquids include saline, phosphate buffered saline (PBS), hyaluronic acid, cellulose ethers (such as carboxymethyl cellulose), collagen, gelatin, autoclaved bone powder, osteoconductive carriers, whole blood, blood fractions, bone marrow aspirate, concentrated bone marrow aspirate, and mixtures thereof. Non-limiting examples of blood fractions include serum, plasma, platelet-rich plasma, concentrated platelet-rich plasma, platelet-poor plasma, and concentrated platelet poor plasma. After hydrating, the bone repair composition becomes a putty or a paste that can be molded into a predetermined shape or administered to a bone defect and manipulated to conform to the bone defect in such a manner that will promote healing. For example, the composition may be hydrated with about 2 ml of saline blood per 2.5 g of combined DBM fibers.

In some embodiments, the bone material can be hydrated by from about 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, 19.0, 19.5, 20.0, 20.5, 21.0, 21.5, 22.0, 22.5, 23.0, 23.5, 24.0, 24.5, 25.0, 25.5, 26.0, 26.5, 27.0, 27.5, 28.0, 28.5, 29.0, 29.5, 30.0, 30.5, 31.0, 31.5, 32.0, 32.5, 33.0, 33.5, 34.0, 34.5, 35.0, 35.5, 36.0, 36.5, 37.0, 37.5, 38.0, 38.5, 39.0, 39.5, 40.0, 40.5, 41.0, 41.5, 42.0, 42.5, 43.0, 43.5, 44.0, 44.5, 45.0, 45.5, 46.0, 46.5, 47.0, 47.5, 48.0, 48.5, 49.0, 49.5, 50.0, 50.5, 51.0, 51.5, 52.0, 52.5, 53.0, 53.5, 54.0, 54.5, 55.0, 55.5, 56.0, 56.5, 57.0, 57.5, 58.0, 58.5, 59.0, 59.5, 60 to about 99.9% w/v, w/w and/or v/v fluid to the desired consistency.

Mixing Device

In various embodiments, a device for mixing a bone material with a liquid is provided. The device comprises a first syringe comprising a first chamber having a proximal end and a distal end. The first chamber comprises a syringe barrel. A bone material is disposed within the chamber. The bone material comprises a DBM pellet of milled and lyophilized demineralized bone fibers. The first syringe comprises a plunger having at least a portion slidably disposed within the proximal end of the chamber and configured to dispense the bone material when mixed with a liquid from the distal end of the chamber, when the plunger is in an extended position, as in FIGS. 10-11.

In some embodiments, the device includes a second syringe comprising a second chamber having a proximal end and a distal end. The second chamber comprises a syringe barrel. A liquid is disposed within the second chamber. The liquid is configured to hydrate the DBM pellet of milled and lyophilized demineralized bone fibers. In some embodiments, the liquid comprises blood, water, saline or a combination thereof. The second syringe comprises a second plunger having at least a portion slidably disposed within the proximal end of the second chamber.

In some embodiments, the device includes a connector fluidly coupling the distal end of the first chamber to the distal end of the second chamber via a dispensing channel and a hydrating channel of the connector. The dispensing channel is coupled to the distal end of the first chamber and the hydrating channel is coupled to the distal end of the second chamber.

Movement of the second plunger to an extended position causes negative pressure (e.g., a vacuum) to be created in the first chamber and the liquid disposed in the second syringe to flow.

The movement of the second plunger to a retracted position forces a gas to move into the second chamber and mix with the liquid. The air and liquid is displaced and pressure is generated in the second chamber causing the second plunger to move in the extended position to cause the fluid to enter the connector's hydrating channel and dispensing channel, and into the first chamber to replace the space from the vacuum. The liquid is mixed with the lyophilized demineralized bone fibers using the negative pressure created in the first chamber by the plunger. The hydration fluid can be 1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 6 mL, 7 mL, 8 mL, 9 mL, 10 mL of fluid or greater. This will hydrate the DBM pellet of milled and lyophilized demineralized bone fibers in the first chamber because it is porous. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers is hydrated in about 60 seconds. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers is hydrated in more than 60 seconds. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers is hydrated in about 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 minutes. Suitable devices that can be used to mix the bone material of the present application are described in U.S. patent application Ser. No. 15/912,038, filed Mar. 5, 2018, now, U.S. Pat. No. 9,913,676, assigned to Warsaw Orthopedic, Inc. Warsaw, Ind., USA. The entire disclosure is herein incorporated by reference into the present disclosure.

The first chamber is detachable from the connector to dispense the hydrated DBM pellet of milled and lyophilized demineralized bone fibers that is moldable to a surgical site. When the first chamber is detached, a cap connected to the distal end of the chamber is removed and the hydrated DBM pellet of milled and lyophilized demineralized bone fibers is ejected from the first chamber, as shown in FIGS. 10-11.

In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers does not contain a binder. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers comprises cartridge milled fibers having a curled portion. In some embodiments, the DBM pellet of milled and lyophilized demineralized bone fibers comprises autograft or allograft bone. In some embodiments, the bone fibers have a diameter from about 100 μm to about 2 mm.

In various embodiments, the bone fibers have a length from about 0.5 mm to about 50 mm. In some embodiments, the bone fibers have an average length from about 0.5 cm to about 10 cm.

In some embodiments, the fibers have an aspect ratio of from about 50:1 to about 1000:1, from about 50:1 to about 950:1, from about 50:1 to about 750:1, from about 50:1 to about 500:1, from about 50:1 to about 250:1, from about 50:1 to about 100:1, from about 10:1 to about 50:1, or from about 5:1 to about 10:1.

In various embodiments, a method of hydrating a bone material with a liquid is provided. The method comprises mixing the liquid with the bone material comprising a DBM pellet of milled and lyophilized demineralized bone fibers in a device. The device comprises a first chamber having a proximal end and a distal end, and the bone material is disposed within the first chamber. A first plunger is provided having at least a portion slidably disposed within the proximal end of the first chamber. The device comprises a second chamber having a proximal end and a distal end. The liquid is disposed within the second chamber. The liquid is configured to hydrate the DBM pellet of milled and lyophilized demineralized bone fibers. A second plunger is provided having at least a portion slidably disposed within the proximal end of the second chamber. The device comprises a connector fluidly coupling the distal end of the first chamber to the distal end of the second chamber, wherein movement of the second plunger to an extended position causes liquid to flow to hydrate the DBM pellet of milled and lyophilized demineralized bone fibers in the first chamber.

The first chamber is detached from the connector to dispense the hydrated DBM pellet of milled and lyophilized demineralized bone fibers that is moldable.

In some embodiments, the mixing device comprises a first syringe and a second syringe. The first syringe comprises a bone material comprising a DBM pellet of milled and lyophilized demineralized bone fibers. The second syringe comprises a liquid, such as blood, saline, sterile water, dextrose, or combination thereof or other physiological fluid that can be used to hydrate the bone material to make it the desired consistency (e.g., moldable putty, paste, gel, etc.). The syringes are connected via a connector. The first and second syringes can engage the connecter via threading, suitable threadings can be in a leur lock fitting, alternatively, there can be a friction or snap-fit fitting so that the syringes can engage the connector and provide a seal that prevents leakage of fluid. In some embodiments, the threading extends radially at discrete positions in the interior of the connector and is configured to engage reciprocal threading of the first and/or second syringe to provide an air-tight seal.

In some embodiments, the device can be monolithic and a single piece. In some embodiments, the first plunger and second plunger can have handles to allow easier mixing between the second chamber and the first chamber. The plungers can be slid longitudinally in their respective chambers one or more times to allow mixing and hydration of the bone material between first and second chambers so as to provide the desired hydration of the bone material.

In some embodiments, the second syringe with fluid can be docked to the first syringe that contains the bone material (e.g., bone graft material to be hydrated). Fluid from the second syringe is introduced into the first syringe that contains the bone graft material and the bone material is hydrated. The second syringe having no more fluid is removed. The first syringe having the bone material and fluid in it is capped. The plunger of the first syringe containing the fluid and the bone material is moved multiple times to pressurize the device and force fluid into graft for the desired hydration. The cap is then removed and the hydrated bone material is removed.

In some embodiments, the device comprises one or more index markers disposed on the first syringe, second syringe, and/or connector to visually indicate alignment of the syringes with the connector and ensure that the chambers and channels are properly aligned for mixing of the bone material and to prevent leakage of liquid and bone material from the device.

In some embodiments, once the syringe containing the mixed bone material and liquid is removed from the connector, a needle can be connected to the syringe and the mixed bone material can be dispensed.

Methods of Treatment

Illustrative bone repair sites that can be treated with implantable compositions of the disclosure include, for instance, those resulting from injury, defects brought about during the course of surgery, infection, malignancy or developmental malformation. The composite bone graft compositions can be used in a wide variety of orthopedic, periodontal, neurosurgical and oral and maxillofacial surgical procedures including, but not limited to the repair of simple and compound fractures and non-unions; external and internal fixations; joint reconstructions such as arthrodesis; general arthroplasty; cup arthroplasty of the hip; femoral and humeral head replacement; femoral head surface replacement and total joint replacement; repairs of the vertebral column including spinal fusion and internal fixation; tumor surgery, e.g., deficit filing; discectomy; laminectomy; excision of spinal cord tumors; anterior cervical and thoracic operations; repairs of spinal injuries; scoliosis, lordosis and kyphosis treatments; intermaxillary fixation of fractures; mentoplasty; temporomandibular joint replacement; alveolar ridge augmentation and reconstruction; inlay osteoimplants; implant placement and revision; sinus lifts; cosmetic enhancement; etc. Specific bones which can be repaired or replaced with the composite bone graft compositions or an implant comprising the compositions include, but are not limited to the ethmoid; frontal; nasal; occipital; parietal; temporal; mandible; maxilla; zygomatic; cervical vertebra; thoracic vertebra; lumbar vertebra; sacrum; rib; sternum; clavicle; scapula; humerus; radius; ulna; carpal bones; metacarpal bones; phalanges; ilium; ischium; pubis; femur; tibia; fibula; patella; calcaneus; tarsal and metatarsal bones.

In accordance with certain aspects of the disclosure, the bone graft compositions of the disclosure can be used as bone void fillers, or can be incorporated in, on or around a load bearing implants such as spinal implants, hip implants (e.g. in or around implant stems and/or behind acetabular cups), knee implants (e.g. in or around stems). In some embodiments, the implantable compositions of the disclosure can be incorporated in, on or around a load-bearing spinal implant device having a compressive strength of at least about 10000 N, such as a fusion cage, PEEK implants, dowel, or other device potentially having a pocket, chamber or other cavity for containing an osteoinductive composition, and used in a spinal fusion such as an interbody fusion. One illustrative such use is in conjunction with a load-bearing interbody spinal spacer to achieve interbody fusion. In these applications, the implantable composition can be placed in and/or around the spacer to facilitate the fusion.

Methods for preparing DBM are well known in the art as described, e.g. U.S. Pat. Nos. 5,314,476, 5,507,813, 5,073,373, and 5,405,390, each incorporated herein by reference. Methods for preparing ceramic powders of calcium phosphate and/or hydroxyapatite are described, e.g., in U.S. Pat. Nos. 4,202,055 and 4,713,076, each incorporated herein by reference.

In some embodiments, the method comprises obtaining the fibers by shaving, milling, or pressing the sheet or block under aseptic conditions. The shape of the fibers can be optimized for inducing new bone formation and handling properties via the network of fibers.

In a still further aspect, the present disclosure provides a method of accelerating bone formation at an implantable tissue regeneration scaffold. In a still further aspect, the present disclosure provides a method of regenerating bone in a patient in need thereof, comprising implanting the patient with the implantable composition.

In a still further aspect, the present disclosure provides a method of treating a bone defect caused by injury, disease, wounds, or surgery utilizing an implantable composition comprising a combination of fibers of demineralized bone matrix obtained from allograft bone, and fibers of non-allograft bone material, the fibers of non-allograft bone material comprising non-fibrous demineralized bone particles embedded within or disposed on the fibers of non-allograft bone material.

Kits

The present application also provides a medical kit for preparing the implantable compositions or the disclosure for treating a patient, the kit including at least a delivery system comprising the bone material as described above and a package enclosing the medical implant device in a sterile condition. Such kits can include a dried material containing the solid ingredients of the composition along with an aqueous medium or other biocompatible wetting liquid for combination with the dried material to form the wetted material, or can include the formulated, wetted implant material in a suitable container such as a syringe or vial (e.g. terminally sterilized), and/or another item such as a load-bearing implant (e.g., a spinal spacer), and/or a transfer device such as a syringe, and/or a therapeutic substance, for example an osteogenic substance such as a BMP. In one specific form, such a medical kit can include a dried material, such as a particulate or dried body, a BMP in lyophilized form (e.g., rhBMP-2), and an aqueous medium for reconstitution of the BMP to prepare an aqueous formulation that can then be added to the dried material in the process of preparing the composite bone graft composition of the disclosure.

The DBM pellet may have functional characteristics. Alternatively, other materials having functional characteristics may be incorporated into the DBM pellet. Functional characteristics may include radiopacity, bacteriocidity, source for released materials, tackiness, etc. Such characteristics may be imparted substantially throughout the DBM pellet or at only certain positions or portions of the DBM pellet.

Suitable radiopaque materials include, for example, ceramics, mineralized bone, ceramics/calcium phosphates/calcium sulfates, metal particles, fibers, and iodinated polymer. Polymeric materials may be used to form the DBM pellet and be made radiopaque by iodinating them. Other techniques for incorporating a biocompatible metal or metal salt into a polymer to increase radiopacity of the polymer may also be used. Suitable bactericidal materials may include, for example, trace metallic elements. In some embodiments, trace metallic elements may also encourage bone growth.

Functional material, such as radiopaque markers, may be provided at one or more locations on the DBM pellet or may be provided substantially throughout the DBM pellet. Thus, for example, in a cylindrical DBM pellet, a radiopaque marker may be provided at a tip of the cylindrical DBM pellet. Such marker may facilitate placement of the DBM pellet. Radiopaque materials may be incorporated into the DBM pellet and/or into the substance for delivery by the DBM pellet. Further, radiopaque materials may be provided at only some locations on the DBM pellet such that visualization of those locations provides indication of the orientation of the DBM pellet in vivo.

The implantable composition of the disclosure can be used alone, as bone grafting materials, as scaffolds for bone tissue engineering for repair, augmentation and replacement of bone tissue or as carriers of growth factors, or carriers of genes.

These and other aspects of the present application will be further appreciated upon consideration of the following Examples, which is intended to illustrate a certain particular embodiment of the application but is not intended to limit its scope, as defined by the claims.

Example 1 Preparation of Injectable Demineralized Bone Matrix Pellets

A method of forming DBM pellet is provided. A large cortical bone is provided. The cortical bone is soaked in specially denatured alcohol (SDA). Then the cortical bone is milled into small pieces of bone, then sieved and cartridge milled into large bone fibers having various sizes. The large bone fibers are sieved to separate out the long fibers having a targeted diameter between about 4 mm to about 0.5 mm. The remainder of the large bone fibers are further cartridge milled to produce short bone fibers having a diameter range between 0.5 mm and 4 mm. The diameters of long fibers are between 0.5 mm and 4 mm and short fibers range from 0.05 mm to 0.5 mm. The long bone fibers and the short bone fibers are mixed in a predetermined ratio. The mixture is demineralized to form a DBM Slurry. The slurry is lightly compacted into a mold to form DBM pellets. The DBM pellets are then freeze dried. Different combinations of long fibers and short fibers are tested for their handling characteristics by measuring the injectable force, as shown in Table 1 below.

TABLE 1 Target Injectable (Long) Fiber Short Fiber Force (wt. %) (wt. %) (lbs.) 80 20 24 90 10 26 100 0 33

The above are ratios/percentages of target (long) and short fibers that have established favorable handling and eject-ability results. A DBM pellet comprising 80% of long bone fibers and 20% of short bone fibers established most favorable handling and ejectability, which can be ideal for an injectable DBM product.

Example 2 Preparation of Injectable Hydrated Demineralized Bone Matrix Pellets

A method similar to Example 1 described above is provided. The DBM pellets are disposed in a mixing device, for example, as shown in FIG. 10. The device comprises a chamber and a plunger. The plunger is moved back and forth between an extended position and a retracted position. The plunger is at the extended position when the distal end of the plunger is close to the distal end of the chamber. The plunger is at the retracted position when the distal end of the plunger is away from the distal end of the chamber. Twenty repeated movements of the plunger are applied to hydrate the DBM pellets. The hydrated DBM pellets are aseptically packaged in a syringe for delivery. The hydrated DBM pellets are tested for material consistencies by measuring the maximum injection force applied to deliver the hydrated DBM pellets, as shown in Table 2 below.

TABLE 2 Hydration Graft volume Max Injection Sample wt. blood volume in syringe force (g) (ml) (ml) (lbs.) 1 3 4.9 19.3 0.99 4.5 6.4 18.1 1 6 7.7 15.6 1.5 4.5 7.2 22.0 1.5 6.75 9.5 22.4 1.51 9 11.9 18.0 1.98 6 9.8 26.7 1.97 9 12.9 20.8

As above, the injection force decreased as hydration volume ratio in syringe increased and the injection force increased as the DBM pellet weight increases

Example 3 Tests of Handling Texture of Hydrated Demineralized Bone Matrix Pellets

A method similar to Example 2 is provided. A texture analyzer, for example, as shown in FIG. 9 is used to qualitatively determine the handling texture of the DBM pellets, as shown in Table 3 below, where a handling score 1 is unacceptable and 5 is excellent.

TABLE 3 Sample # Handling Score TA Handling Number Control (Grafton DBF) n/a 858 Sample Set# 1 (DOE 1): 2.8 731 100% of 3-5 cm fibers Sample Set # 2 (DOE 2): 2.4 483 5% of 3-5 cm fibers, 30% of 1.5-3 cm fibers, 50% of 5 mm-1 cm fibers, and 15% of 0.106 powder Sample Set # 3 (DOE 3): 2.8 827 100% of 1.5-3 cm fibers Sample Set # 4 (DOE 4): 2.8 936 50% of 1.5-3 cm fibers and 50% of 5 mm-1 cm fibers Sample Set # 5 (DOE 5): 1.6 480 33% of 1.5-3 cm fibers, 33% of 5 mm-1 cm, and 33% of 0.106 powder

Handling texture quality declines as short fiber % increases, but lower short fiber % increases waste from the donor bone. These samples were hydrated at a 100% hydration ratio which was determined to decrease the handling texture to an unacceptable level. Further texture quality testing determined that the best range for handling texture was from 50-75% hydration.

Example 3 Tests of Handling Characteristic of Hydrated Demineralized Bone Matrix Pellets

A method similar to Example 3 is provided. Additionally, varying percentages of short fibers added to the DBM pellet formulation for injection, force measurement and qualitative handling texture are tested as shown in Table 4 below.

TABLE 4 Injection Peak force Handling Rank Samples % Short Fibers (lbs.) (1 = best; 3 = worst) a 10 24 1 b 20 26 3 c 0 33 2

As shown in Table 4, a formulation having 33% short bone fibers before texture assessment falls below an acceptable level while having 100% targeted long bone fiber lengths will still inject under 50 lbs. of thumb pressure. The combination of 10% short fibers and 90% long fibers had the best handling rank.

It should be understood that the forgoing relates to exemplary embodiments of the disclosure and that modifications may be made without departing from the spirit and scope of the disclosure as set forth in the following claims. 

What is claimed is:
 1. A method of preparing a demineralized bone matrix pellet, the method comprising providing a plurality of long bone fibers having a diameter from about 0.5 mm to about 8.0 mm; mixing the plurality of long bone fibers with a plurality of short bone fibers having a diameter from about 0.5 mm to about 0.05 mm to form a mixture of long bone fibers and short bone fibers; demineralizing the mixture of long bone fibers and short bone fibers to form a demineralized bone matrix slurry; and drying the demineralized bone matrix slurry to form a demineralized bone matrix pellet.
 2. The method of claim 1, wherein the demineralized bone matrix slurry is added to a mold and dried in the mold.
 3. The method of claim 1, wherein the demineralized bone matrix slurry is compacted into a mold using a pressure from about 4 to about 65 Newtons.
 4. The method of claim 1, wherein the slurry is added to a mold to form the demineralized bone matrix pellet and the pellet is removed from the mold and lyophilized.
 5. The method of claim 4, further comprising rehydrating the lyophilized demineralized bone matrix pellet with physiologically acceptable liquid to form an injectable demineralized bone matrix.
 6. The method of claim 5, wherein the liquid comprises bone marrow aspirate, saline, sterile water, blood for injection, phosphate buffered saline, dextrose, Ringer's lactated solution, or a combination thereof.
 7. The method of claim 6, wherein the blood volume comprises from about 3 mL to about 9 mL.
 8. The method of claim 5, wherein an injection force to inject the injectable demineralized bone matrix is from about 15 lbs. to about 33 lbs. or from about 24 lbs. to about 27 lbs.
 9. The method of claim 1, wherein the demineralized bone matrix pellet comprises from about 0.1 wt. % to about 33 wt. % short demineralized bone fibers and from about 80 wt. % to about 99.9 wt. % long demineralized bone fibers based on a total weight of the bone fibers or based on a total weight of the demineralized bone matrix pellet.
 10. The method of claim 1, wherein the demineralized bone matrix pellet comprises from about 0 wt. % to about 33 wt. % short demineralized bone fibers and from about 80 wt. % to about 100 wt. % long demineralized bone fibers based on a total weight of the bone fibers or based on a total weight of the demineralized bone matrix pellet.
 11. The method of claim 3, wherein the compacting comprises (i) applying pressure to the mixture manually with a spatula or a roller and compression block; or (ii) allowing the demineralized bone matrix slurry to drain in a sieve until excess fluid has drained from the slurry, without applying pressure.
 12. The method of claim 1, wherein the ratio of long demineralized bone fibers to short demineralized bone fibers is from about 100:0 to about 80:20 respectively or about 90:10 respectively.
 13. A bone material comprising a mixture of a plurality of long bone fibers having a diameter from about 0.5 mm to about 8.0 mm and a plurality of short bone fibers having a diameter from about 0.5 mm to about 0.05 mm.
 14. The bone material of claim 13, wherein the long bone fibers and the short bone fibers are in a ratio from about (i) 100:0 to about 80:20 respectively or (ii) about 90:10 respectively.
 15. The bone material of claim 14, wherein the bone material is demineralized and molded into a lyophilized demineralized bone matrix in pellet form.
 16. The bone material of claim 14, further comprising demineralized bone powder, wherein the demineralized bone powder has a diameter of about 0.106 mm and below.
 17. The bone material of claim 15, further comprising hydrating the bone material with liquid to an injectable viscosity of from about 50 Pa-s to about 3000 Pa-s.
 18. The bone material of claim 16, wherein the demineralized bone powder is from about 15 wt. % to about 33 wt. % based on a total weight of the bone material.
 19. The bone material of claim 15, wherein the demineralized bone matrix pellet comprises from about 0.01 wt. % to about 33 wt. % short demineralized bone fibers and from about 80 wt. % to about 99.99 wt. % long demineralized bone fibers based on a total weight of the bone fibers or based on a total weight of the demineralized bone matrix pellet.
 20. The bone material of claim 19, wherein the pellet is hydratable with a liquid comprising bone marrow aspirate, saline, sterile water, blood for injection, phosphate buffered saline, dextrose, Ringer's lactated solution, or a combination thereof. 